This invention is in the field of electrical safety for electrical home appliances of many types, including food preparation apparatus, personal care and convenience devices, and power tools. Examples of these many devices include hand-held hair dryers, shavers, electric toothbrushes, toasters, canopeners, blenders, heaters, fans, drills and sanders.
Particularly when personal care electrical products are used in a bathroom there exists a danger that an appliance which is plugged in but switched-off, may fall into a sink or tub of water and cause the user electric shock, burns or electrocution.
Both children and adults often err in thinking that a switched-off but plugged-in appliance is safe. Obviously the switch itself remains "hot", and thus the appliance remains dangerous.
Efforts and techniques currently used to try to reduce this danger include use of relatively short power cords to reduce the likelihood of a plugged-in product ever reaching the water; water proofing the switch and upstream circuitry; double-grounding the appliance; and using a ground fault interrupter.
Despite the incremental benefits or potential benefits from each of these techniques, none has been satisfactory when considering the practical reality of trying to implement such changes. Short power cords usually create such inconvenience for the user that the person will either purchase a competitive product with a longer cord or add an extension cord.
To waterproof the switch and upstream circuitry would require sealing parts of the appliance, which would be unacceptably expensive and usually would be impossible since the electric motors, where used, need air circulation for cooling. Double grounding the housing of an appliance may protect one person holding an appliance, but would not protect a person in a tub of water where the plugged-in appliance falls.
Finally, ground fault interrupts, while quite effective, are likely to cost more than the appliance itself, in addition to adding bulk and inconvenience for the user. As a result of such practical considerations, these devices have not been widely used.